Process for the production of amino silicate compounds and their condensation products

ABSTRACT

Silicic-amino compounds are formed by the chemical reaction of silicic acid with amino compounds in the presence of a suitable alkali at a suitably elevated temperature, and then by reacting the resultant compounds with an aldehyde, a condensation product is formed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. Pat. application Ser. No.652,338, filed Jan. 26, 1976, U.S. Pat. No. 4,033,938 which is acontinuation-in-part of my copending application, Ser. No. 559,313,filed Mar. 17, 1975 U.S. Pat. No. 3,979,362, which is acontinuation-in-part of my earlier U.S. patent application, Ser. No.71,628, filed Sept. 11, 1970, now abandoned.

BACKGROUND OF THE INVENTION

This invention relates in general to silicic acid compounds and, morespecifically, to a process for producing novel silicic amino compoundsand their condensation products.

The silicic acid may be produced by any of the well known processes,such as chemically reacting a solution of sodium metasilicate with amineral acid to produce silicic acid gel. Various silicic acids may beused, such as silicic acid gel, orthosilicic acid, metasilicic acid,polysilicoformic acid, orthosilicoformic acid, silicoformic acid andmonosilandiol.

Amino silicate compounds are useful as intermediates for the productionof other compounds by further suitable reactions. Typically, they may beused in the production of prepolymers, polymers, resins, as an additiveor a reactant. Also, they may be used in coating agents, adhesives,impregnants, molding powder, paints, varnishes, laminates, or theirmanufacture, and may be reacted with other polymerizing compounds.

The silicic-amino aldehyde condensation polymers are useful as coatingagents, adhesives, impregnants, molding powder, paints varnishes,laminates or their manufacture, and may be reacted with otherpolymerizing compounds.

SUMMARY OF THE INVENTION

I have discovered that silicic acid will react chemically with an aminocompound in the presence of a suitable alkali catalyst at a temperaturejust above the melting point of the amino compound. The amino compoundsare basic and will react chemically with silicic acid without an alkalicatalyst, but the reaction is enhanced by a suitable alkali catalyst.The amino compound will react with silicic acid in the ratio of 1:1 molsor 2:1 mols. While the specific reaction which takes place is not fullyunderstood, typical reactions which are believed to occur take place asfollows:

Orthosilicic acid is theorized to react with urea as follows:

    Si(OH).sub.4 +NH.sub.2.CO.NH.sub.2 →HO.SiO.NH.CO.NH.sub.2 +2H.sub.2 O

metasilicic acid is theorized to react with urea as follows:

    HO.SiO.OH+NH.sub.2.CO.NH.sub.2 →HO.SiO.NH.CO.NH.sub.2 +H.sub.2 O

    ho.siO.OH+2NH.sub.2.CO.NH.sub.2 →NH.sub.2.CO.NH.SiO.CO.NH.sub.2 +2H.sub.2 O

    2ho.siO.OH+NH.sub.2 CO.NH.sub.2 →HO.SiO.NH.CO.NH.SiO.OH+2H.sub.2 O

reactions with other amino compounds are expected to be similar tothese, so that the mol ratios of the reactants should be selectedaccordingly.

Amino silicate compounds are theorized to react with an aldehyde to formcondensation products as follows:

Urea silicate is theorized to react with formaldehyde as follows:##STR1##

DETAILED DESCRIPTION OF THE INVENTION

Any suitable amino compound may be used in my novel process. Typicalamino compounds include urea, thiourea, melamine, quanidine, saccharin,propyl urea, butyl urea, benzene and tolune sulfonamide, ammeline,aliphatic diamines and other alkyl-substituted ureas.

Various aldehydes may be used, such as formaldehyde, acetaldehyde,butyaldehyde, chloral, acrolein, furfural and hexamethylene tetramine.The aldehyde ratio may vary from 1:1 to 5:1 when reacting with an aminosilicate, depending on the methyl groups desired.

The chemical reaction between silicic acid and an amino compound maytake place in a basic, neutral or acidic pH, but it is enhanced by abasic pH. The chemical reaction between an amino silicate and analdehyde may take place in a basic, neutral or acidic pH, but isenhanced by a basic or an acidic pH. The acidic catalysts most commonlyused are sodium hydrogen sulfate, sulfuric acid, hydrochloric acid,formic acid, acetic acid, and acid esters, such as acid alkylphosphates. The most common basic catalyst is sodium carbonate, butother basic compounds may be used, such as calcium hydroxide, sodiumhydroxide, potassium carbonate, potassium hydroxide, ammonia andalkanolamine. The alkali may act as a catalyst directly, or it may reactslightly with one or the other of the primary reactants. From about 1 to10 weight percent catalyst, based on the weight of silicic acid andamino compound used, gives best results.

The resin solutions of poly (aldehyde amino silicate) may be convertedto a fully hardened state by prolonged heating. Plasticizers may be usedto improve flexibility and adhesiveness. Latent catalysts may be used tocatalyze the final conversion of the molding powder from the initialstages of resin formation to the infusible, insoluble product. An excessamount of silicic acid may be used as a filler.

The amino silicate compounds may also from condensation products withacetones, furans, isocyanates, diisocyanates, epichlorohydrin,dicarboxylic acids and anhydrides, silicones, and may be copolymerizedwith unsaturated organic compounds.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following examples describe in detail certain preferred embodimentsof the process of my invention. These preferred processes may, ofcourse, be varied as described above with similar results. Parts andpercentages are by weight, unless otherwise indicated.

EXAMPLE I

Forty parts by weight of sodium silicate pentahydrate are added to 200parts by weight of water, stirred until the sodium silicate goes intosolution, then dilute sulfuric acid is added until the pH is 4 to 6,thereby producing silicic acid gel. The silicic acid gel is washed andfiltered. The moist silicic acid gel is mixed with 20 parts by weight ofurea, heated to 90° to 150° C. for 20 to 60 minutes, until the chemicalreaction is substantially complete, at ambient pressure, therebyproducing a white, granular compound, urea silicate (H₂ N.CO.NH.SiO.OH).

The said urea silicate is mixed with an aqueous formaldehyde solution inthe ratio of 1:1 mols, heated to 70° to 100° C. while agitating, for 20to 60 minutes, or until the desired viscosity is reached, therebyproducing poly (formaldehyde urea silicate) resin, which is clear incolor and may be produced as a thick liquid or as a solid.

The clear liquid of said resin may be used as an adhesive for wood andalso may be used as a protective coating for wood. The solid resin maybe softened with heat and molded into useful objects. The said resin issoluble in acetic acid and may be used as a varnish or paint to protectwood; it leaves a tough, clear resin on the wood when dry.

EXAMPLE II

Twenty-five parts by weight of silicic acid gel as produced in ExampleI, that has been air dried at 25° to 50° C., and 20 parts by weight ofurea are mixed, heated to above the melting point of urea for 20 to 60minutes, while agitating, until the chemical reaction is substantiallycomplete, thereby producing urea silicate, a white, granular compound.

The said urea silicate is added to an aqueous solution of formaldehydein the ratio of 1:1.5 mols, mixed, and the urea silicate goes intosolution. The unreacted silicic acid is removed by filtration. About 15%to 25% of the said silicic acid did not chemically react with said urea.To the clear aqueous solution of urea silicate and formaldehyde is addeda dilute solution of sulfuric acid until the pH is 4 to 5, then saidsolution is heated to 70° to 110° C. for 20 to 80 minutes, until thedesired viscosity is obtained, thereby producing poly (formaldehyde ureasilicate) resin, which is clear in color and may be produced as a thickliquid or as a solid. The said solid resin may be heated to 70° to 80°C. and molded into useful objects.

EXAMPLE III

About one mol of gelatinous orthosilicic acid, one mol of urea and about0.2 mol of sodium carbonate are mixed, heated to 95° to 150° C. for 20to 60 minutes, thereby producing white granules of urea silicate.

The urea silicate granules are only slightly soluble in water, but aresoluble in warm aqueous solution of formaldehyde. A small portion (15%to 30%) of the said urea silicate is not soluble in an aqueous solutionof formaldehyde and appears to be urea disilicate. The urea disilicatewill react with an aqueous solution of formaldehyde to produce a clearresin. About 10% to 25% of the said gelatinous orthosilicic acid doesnot chemically react with the said urea. The said urea silicatedecomposes with further heating and ammonia is given off. Urea silicateis soluble in alkali hydroxide solution, dilute sulfuric acid and othersolvents.

EXAMPLE IV

One mol by weight of metasilicic acid and one mol by weight of urea aremixed, heated to 95° to 150° C. for 20 to 60 minutes, until the reactionis substantially complete, thereby producing white granules of ureasilicate. The said urea silicate is mixed into about one mol ofacetoaldehyde in an aqueous solution and the urea silicate goes intosolution. The unreacted metasilicic acid is filtered out. About 15% to25% of said metasilicic acid is filtered out. The urea silicateformaldehyde solution is heated to 70° to 110° C. for 20 to 60 minutes,until the desired viscosity is obtained, thereby producing poly(formaldehyde urea silicate) resin. The resin may be produced as a thickclear resin or a solid, depending on the length of time the resin isheated.

EXAMPLE V

Clay is reacted with sulfuric acid, thereby producing metasilicic acid,which is recovered by filtration. About one mol of said metasilicic acidis mixed with 2 mols of urea, heated to 90° to 150° C. for 20 to 30minutes, thereby producing white granules of diurea silicate. The saiddiurea silicate is added to an aqueous solution of hexamethylenetetramine in the ratio of 1:1.5 mols, heated to 70° to 110° C. for 20 to90 minutes, thereby producing a clear thick solution of poly(formaldehyde diurea silicate) resin, and, upon further heating, a whiteresin is produced. The said white resin is soluble in acetic acid andproduces a clear solution; the unreacted silicic acid is precipitated.The solution of poly (formaldehyde diurea silicate) resin forms a cleartough coating on wood.

EXAMPLE VI

Moist silicic acid gel containing equivalent to about one mol of silicondioxide with a pH of 6.5 to 8, is mixed with one mol of melamine, heatedto 70° to 260° C., while mixing, for 20 to 60 minutes, thereby producinga white, fine, granular compound, melamine silicate. The said melaminesilicate is added to about 5 mols for aqueous formaldehyde, heated to70° to 120° C. for 30 to 90 minutes, the melamine silicate goes intosolution; the solution is filtered, and about 5% to 15% of the saidsilicic acid gel is filtered out. The said solution is heated until themelamine silicate reacts chemically with the formaldehyde to producewhite granules of poly (formaldehyde melamine silicate) resin. Onfurther heating, the said resin melts and produces a soft pliable resin.

The poly (formaldehyde melamine silicate) resin has a melting point of80° to 90° C., is soluble in glacial acetic acid and, when heated withglacial acetic acid, it reacts chemically to produce rubbery, solidresin. Poly (formaldehyde melamine silicate) resin will react chemicallywith organic acids and anhydrides to produce novel and useful resins.The said resin may be melted and molded into useful objects.

EXAMPLE VII

Moist silicic acid gel containing about 1 mol of silicon dioxide and onemol of malamine are mixed, sodium carbonate is added until the pH is 8to 10.5, then heated to 70° to 260° C. for 20 to 90 minutes, whileagitating, thereby producing fine granules of melamine silicate. Thesaid melamine silicate is added to about 2 mols of aqueous formaldehyde,heated to 70° to 150° for 30 to 120 minutes, while agitating, and themelamine silicate goes into solution. On further heating, a white, soft,granular resin, poly (formaldehyde melamine silicate) is produced.

The said poly (formaldehyde melamine silicate) resin is soluble inacetic acid and may be painted on wood to produce a hard, clearprotective coating. The granules of poly (formaldehyde melaminesilicate) resin soften or melt at 70° to 90° C. and can be molded intouseful objects or coatings, which are resistent to strong acids andalkalis.

EXAMPLE VIII

The said melamine silicate as produced in Example VII is added to about2 mols of formaldehyde in an aqueous solution and dilute sulfuric acidis added until the pH is 4 to 5.5, then heated to 70° to 100°, whileagitating, for 15 to 60 minutes, thereby producing a white, solid resin,poly (formaldehyde melamine silicate). The said resin is not soluble inacetic acid and is resistent to strong acids and alkalis. On heating,the said resin softens very little and is destroyed before it will melt.

EXAMPLE IX

Concentrated sulfuric acid is slowly added to 40 parts by weight ofsodium metasilicate pentahydrate granules, while agitating, until the pHis 6.5 to 7.5. The said mixture is washed with water, filtered, therebyproducing a mixture of polysilicoformic acid, orthosiliconformic acid,silicoformic acid and metasilicic acid. The said mixture is mixed with30 parts by weight of melamine then heated to 70° to 260° C. for 20 to90 minutes, thereby producing white granules of melamine silicoformateand melamine metasilicate.

About 120 parts by weight of a 37% aqueous solution of formaldehyde isadded to said granules of melamine silicoformate and melaminemetasilicate and then heated to 70° to 120° C., while agitating, for 20to 120 minutes, thereby producing a white resin, poly (formaldehydemelamine silicoformate and metasilicate). The said resin is soluble inacetic acid, softens with heat, and may be molded into useful objects.

EXAMPLE X

The silicoformic acid, polysilicoformic acid and metasilicic acid asproduced in Example IX are mixed with 25 parts by weight of urea, heatedto 90° to 150° C., while agitating, for 20 to 90 minutes, until thechemical reaction is substantially complete, thereby producing whitegranules of urea silicate and urea silicoformate. The said whitegranules are added to about 100 parts by weight of a 37% aqueousformaldehyde solution, then heated to 70° to 120° C., while agitating,for 20 to 90 minutes, or until the desired viscosity is obtained,thereby producing a poly (urea silicate urea silicoformate formaldehyde)resin, which may be a clear thick liquid or a clear solid.

The said resin is soluble in a glacial acetic acid. About 10% to 20% ofthe silicic acid is not soluble and may be filtered out. The acetic acidsolution of said resin may be painted on wood and forms a hard, clearprotective coating.

EXAMPLE XI

The silicoformic acid, polysilicoformic acid and metasilicic acid asproduced in Example IX are mixed with 30 parts by weight of thiourea,heated to 70° to 150° C., while agitating, for 15 to 90 minutes, therebyproducing white granules of thiourea silicoformate and thioureasilicate. The said thiourea silicate and silicoformate are added to 100parts by weight of 37% aqueous solution of formaldehyde, heated to 70°to 90° C. and the solution becomes clear. The said solution is filteredand about 10% to 20% of the silicic acid is filtered off. Dilutesulfuric acid is added to said solution until the pH is 4 to 5, and thenheated to 70° to 90° C., while agitating, for 20 to 30 minutes, or untilthe desired viscosity is obtained. The resin is, at first, clear, then,as the viscosity increases, it becomes white, thereby producing poly(formaldehyde thiourea silicate thiourea silicoformate) resin. The saidresin is soluble in acetic acid and forms a clear solution. The saidwhite resin has a softening point of 40° to 50° C., depending on itsviscosity while heating, and may be molded into useful objects or usedas a protective coating agent.

EXAMPLE XII

Moist silicic acid gel containing about 20 parts by weight ofmetasilicic acid is mixed with 25 parts by weight of dicyandiamide,heated to 70° to 220° C. for 20 to 90 minutes, while stirring, therebyproducing a light yellow powder, dicyandiamide silicate. Dicyandiamidesilicate is added to aqueous formaldehyde in about equal molarproportions, heated to 70° to 150° C., while agitating, for 25 to 120minutes, or until the desired viscosity is obtained, thereby producing aclear resin, poly (dicyandiamide silicate), which turns to a creamycolor upon cooling. The poly (dicyandiamide silicate) resin is solublein acetic acid and forms a clear solution with 15% to 25% of the silicicacid settling to the bottom and which may be filtered out. The saidresin softens at about 50° to 60° C. and may be molded into usefulobjects or used as a coating agent on wood.

EXAMPLE XIII

Dicyandiamide silicate as produced in Example XII is added to an aqueoussolution of formaldehyde in the ratio of 1:1 mols. Dilute hydrochloricacid is added to the said solution until the pH is 4 to 5. The saidmixture is heated to 70° to 100° C. for 20 to 60 minutes, whileagitating, thereby producing a white resin poly (formaldehydedicyandiamide silicate). The said resin softens with heat, is soluble inacetic acid and, when the acetic acid solution of said resin is appliedto wood and dries, it leaves a clear protective coat.

EXAMPLE XIV

Concentrated phosphoric acid is added slowly to about 40 parts by weightof sodium metasilicate containing less than 6 mols of water per mol ofsodium metasilicate, while agitating to control the temperature, untilthe pH is about 6.5 to 7.5, thereby producing a mixture ofpolysilicoformic acid, orthosilicoformic acid, silicoformic acid,metasilicic acid and sodium phosphate. The mixture is washed andfiltered to remove the sodium phosphate. The said mixture of silicicacids are mixed with 25 parts by weight of urea and 75 parts by weightof an aqueous solution containing 37% formaldehyde. Sodium hydrogensulfate is added until the pH is 4 to 5, the said mixture is then heatedto 50° to 80° C. for 20 to 50 minutes, while mixing, or until thedesired viscosity is obtained. The resin is first clear, then, as theviscosity increases, it becomes white, thereby producing poly(formaldehyde urea silicate urea silicoformate) resin. The said resin issoluble in acetic acid and forms a clear solution, about 10% to 20% ofthe silicic acid is not soluble and may be filtered out. The acetic acidsolution of said resin may be applied to wood and, when dried, producesa clear tough protective coating. The said resin softens with heat at60° to 70° C. and may be molded into useful objects.

EXAMPLE XV

The mixture of polysilicoformic acid, orthosilicoformic acid,silicoformic acid and metasilicio acid as produced in Example XIV aremixed with 30 parts by weight of melamine and added to 100 parts byweight of an aqueous solution containing about 37% formaldehyde, thendiluted sulfuric acid is added until the pH is 4 to 6. The mixture isheated to 70° to 100° C., while agitating; the silicic acids andmelamine go into solution, and, in 20 to 60 minutes or until the desiredviscosity is obtained, produces a white poly (formaldehyde melaminesilicate melamine silicoformate), resin. The said resin softens withheat and may be molded into useful objects. The said resin is soluble inacetic acid and, when applied to wood and dried, it produces a toughclear protective coating.

EXAMPLE XVI

The mixture of polysilicoformic acid, orthosilicoformic acid,silicoformic acid and metasilicic acid as produced in Example IX, 30parts by weight of dicyandiamide and 100 parts by weight of an aqueoussolution containing about 37% formaldehyde are mixed, then acetic acidis added until the pH is 4 to 5. The said mixture is heated to 70° to100° C., while stirring, for 20 to 60 minutes or until the desiredviscosity is obtained, thereby producing white poly (formaldehydesilicate dicyandiamide silicoformate) resin. The said resin is solublein acetic acid and, when applied to wood and dried, it leaves a clear,hard protective coat. The said resin softens with heat and may be moldedinto useful objects.

EXAMPLE XVII

The mixture of polysilicoformic acid, orthiosilicoformic acid,silicoformic acid and metasilicic acid as produced in Example IX aremixed with 25 parts by weight of urea, then 40 parts by weight ofacrolein is added. The pH is adjusted to a pH of 4 to 5 with sodiumhydrogen sulfate. The said mixture is then heated to 60° to 80° C. for20 to 60 minutes, while agitating, thereby producing a light yellow poly(acrolein urea silicate urea silicoformate) resin. The said resin issoluble in acetic acid and may be molded into useful objects by heat andpressure.

EXAMPLE XVIII

The mixture of polysilicoformic acid, orthosilicoformic acid,silcoformic acid and metasilicic acid as produced in Example IX, 30parts by weight of urea and 40 parts by weight of crotonaldehyde aremixed; the pH is adjusted to a pH of 4 to 5 with dilute hydrochloricacid and the said mixture is heated to 50° to 85° C. for 20 to 60minutes or until the desired viscosity is obtained, thereby producinglight yellow poly (crotonaldehyde urea silicate urea silicoformate)resin. The said resin is soluble in acetic acid and softens with heat.The acetic acid solution of said resin may be used as a protectivecoating on wood.

EXAMPLE XIX

The mixture of polysilicoformic acid, orthosilicoformic acid,silicoformic acid and metasilicic acid as produced in Example IX, 20parts by weight of urea and potassium carbonate are added until the pHis 8 to 10, mixed, heated to 90° to 150° C. for 20 to 60 minutes, whilestirring, thereby producing a mixture of urea disilicate and ureadisilicoformate. About 80 parts by weight of an aqueous solutioncontaining 37% formaldehyde is added to said urea disilicate and ureadisilicoformate, heated to 80° to 100° C., while stirring, for 30 to 90minutes or until the desired viscosity is reached, thereby producingpoly (formaldehyde urea disilicate urea disilicoformate) resin.

EXAMPLE XX

Two mols of orthosilicic acid, one mol of urea, and 0.1 mol of sodiumcarbonate are mixed, heated to just about the melting point of urea,while agitating, for 20 to 60 minutes, thereby producing a white,granular compound, urea disilicate (HO.SiO.NH.CO.NH.SiO.OH).

The said urea disilicate is added to an aqueous solution offormaldehyde, containing about 1.5 mols of formaldehyde, mixed, heatedto 70° to 110° C. while agitating for 20 to 90 minutes or until thedesired viscosity is obtained, thereby producing poly (formaldehyde ureadisilicate) resin.

Although certain specific preferred ingredients and conditions aredescribed in conjunction with the above-detailed description of theinvention and Examples, these may be varied and other ingredients may beused, where suitable, with similar results.

Other applications, modifications and ramifications of this inventionwill occur to those skilled in the art upon reading this disclosure.These are intended to be included within the scope of this invention, asdefined in the appended claims.

I claim:
 1. The process for the production of poly(aldehyde aminosilicate) resinous products by the following steps:(a) mixing about 10parts by weight if silicic acid, weight calculated on the basic of drysilicic acid, and from about 5 to 20 parts by weight of an aminocompound selected from the group consisting of urea, thiourea, melamine,aniline, dicyanidiamide, alkyl-substituted ureas and mixtures thereof;(b) heating said mixture to a temperature of from about 70° C. to abovethe melting point, but below the boiling point of the amino compound,for at least 20 minutes; thereby (c) producing an amino silicatecompound; (d) adding an aldehyde to the amino silicate compound in theratio of 1 to 5 mols to each mol of the amino silicate compound; (e)heating said mixture to a temperature of from about 70° C. to 150° C.,while agitating for at least about 20 minutes, thereby (f) producing apoly(aldehyde amino silicate) resinous product.
 2. The method of claim1, wherein said silicic acid is selected from the group consisting ofsilicic acid gel, orthosilicic acid, metasilicic acid, polysilicoformicacid, orthosilicoformic acid or mixtures thereof.
 3. The method of claim1, wherein an alkali compound, selected from the group consisting ofsodium carbonate, sodium hydroxide, potassium carbonate, sodium silicateand mixtures thereof,
 4. The process of claim 1, wherein the aldehyde isselected from the group consisting of acetaldehyde, butyaldehyde,acrolein, and furfural.